Our Fight‑or‑Flight Response Is More Than Just Instinct, Scientists Find
Humans’ fight-or-flight response to stressful or frightening situations may be triggered by the nervous system, but our ability to act upon it is governed by a specific regulatory protein, a new study has found.
Published in Proceedings of the National Academy of Sciences, the study found that a protein — called fast skeletal myosin binding protein-C, or simply fMyBP-C — regulates the body’s fast-twitch muscles and can be found in both the heart and the skeletal system. These fast-twitch muscles are the ones in charge of fight-or-flight responses requiring sudden bursts of power, like sprinting or jumping, as opposed to slow-twitch muscles that help with long-term activities requiring endurance, like bicycling.
“Our study concludes that [the protein] is essential in regulating the force generation and speed of contraction of fast muscles,” Sakthivel Sadayappan, a professor in the cardiovascular health division at the University of Cincinnati, in the U.S., said in a statement. In fact, when the scientists deactivated, or disrupted, this protein in mice, they noticed a “reduced ability to exercise, less maximal muscle force, and a diminished ability for the muscle to recover from injury,” Sadayappan added.
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In humans, this is the protein that helps muscle force generation, or the process by which skeletal muscles respond to neural stimuli. And, as Sadayappan explains, this muscle response can be critical to our survival. “Just imagine, you are walking through a forest and suddenly you see a tiger in front of you. … You will immediately act, either to fight or run away from the animal. For that action, fast muscle is essential, and [the protein] is the key molecule to regulate the speed of action,” he says.
While being attacked by tigers may not be the likeliest example for a lot of us, the same protein also regulates our reaction to, say, a growling dog on the street, or a sudden obstacle to our commutes. But over time, people can lose the ability of muscle force generation due to a host of reasons ranging from being extremely inactive, being hospitalized for long periods of time, or even aging.
In addition to giving us an insight into the biological processes governing our fight-or-flight response, the findings can also pave the path for new ways to treat certain muscular disorders. “We think if we can manipulate the workings of [the protein] in skeletal muscle that we can prevent or at least slow down the loss of muscle function in genetic muscle disease such as distal arthrogryposis. Our research is trying to figure out this problem in human health,” Sadayappan notes.